Angiography procedures in general require a device for introducing a radiopaque fluid into a body conduit. Radioscopic visualization of this fluid in the conduit provides a picture of the interior shape of the conduit and, more importantly, a view of any obstructions which may be occluding the conduit. This process is particularly important in a procedure which is commonly referred to as cholangiography where the bile ducts are infused with the radiopaque fluid to show obstructions such as gallstones.
Although gallstones are of mixed composition, their most common constituent appears to be cholesterol. Under normal circumstances this cholesterol is prevented from flowing out of the body by a delicate balance of bile salts and phospholipids. However, change in this balance can produce a increase in cholesterol and a decrease in bile salts; this generally leads to formation of the gallstones.
These stones can remain in the gall bladder for many years without causing distress, but sometimes a gallstone slips out of the gall bladder into the biliary tree. If this stone is too large to pass easily through the bile duct, it may cause an obstruction to the flow of bile, an extremely serious problem.
Biliary obstruction due to stones is one of the more common causes of jaundice. Any obstruction of the bile duct causes the bile to back up in the biliary tree eventually making it impossible for the liver cells to secrete bile. Thus the bile builds up and the substances which produce the bile begin to collect in the blood stream. This eventually results in the yellowing which characterizes jaundice.
Since gallstones most commonly form in the gall bladder, it is sometimes desirable to sacrifice the normal function of the gall bladder (to collect and concentrate the bile) in favor of removing this stone-producing organ. In a procedure called cholecystectomy, the cystic duct, which connects the gall bladder to the common bile duct, is ligated and the gall bladder is removed from the body along with any stones in the gall bladder.
In order to fully address the gallstone problem, this procedure requires that the physician also view the system of ducts, commonly referred to as the biliary tree, for any stones which may have already migrated from the gall bladder. A cholangiography catheter is inserted through an incision in the cystic duct. The radiopaque fluid is injected through the catheter into the cystic duct and on to the biliary tree. Of course it is important to maintain this fluid in the ducts long enough to permit the necessary visualization. In order to seal the cystic duct and thereby prevent retrograde flow of the radiopaque fluid, a staple or ligating loop is typically applied between the point of incision and the distal injection port of the catheter.
This initial staple is loosely applied before the catheter is inserted and the catheter is moved through the duct and the loose staple. Then a second staple is applied tightly around the duct and the catheter. It requires a high degree of skill to apply the initial staple tight enough to obstruct the duct but loose enough to permit insertion of the catheter. It takes even more skill to tighten the second staple sufficiently to occlude the duct around the catheter but loose enough to avoid collapsing the catheter prior to injection of the fluid.
A significant need has remained for a device which can inject radiopaque fluid into a body conduit and form a seal within the conduit to prevent retrograde flow of the injectate. A device which cannot only provide such a seal but also anchor the catheter in this position would be of particular advantage.